We were supposed to stay one month in January but after staying a few days decided to extend one more month.
Sumanaz place is beautiful. The appartment is big enough for two people, really clean and you have everything you need from a microwave, to kitchen supplies to a table and couch and TV. Also the Bed is one of the most comfortable I have ever slept in. The view of the appartment into a green garden is also quite nice in comparison to the usual city vibe.
Apart from the appartment is the location really awesome. You have a 7/11 one minute away and some really amazing street food and good restaurants. You will also find everything else you need from pharmacy, to copy shop and massage in the same road. It's close to shopping malls and lumpini park for some evening sport. Also will you find every embassy or language school around the corner in case that you have to do some bureaucratic stuff.
Sumana is super easy to contact and answers almost immediately. communication with her was never a problem. besides that is she extraordinarily helpful and will do her best to make your stay great.
We really loved our stay here and can only recommend it, especially for that price. you wont find anything better in Sathorn area.